As shown in FIG. 8, a conventional fuel cell system includes a hydrogen generator 81 and a fuel cell 82. The hydrogen generator 81 generates a hydrogen-containing gas by a reforming reaction using as a raw material a hydrogen-containing organic compound, such as a city gas. The fuel cell 82 generates electric power using the hydrogen-containing gas supplied from the hydrogen generator 81 and an oxidizing gas. The fuel cell system is normally configured such that a combustible anode off gas discharged from the fuel cell 82 is combusted in a combustor, and heat necessary for the reforming reaction is supplied to the hydrogen generator 81. A CO sensor 85 is normally used to confirm combustion stability of the combustor 83. If moisture in a flue gas discharged from the combustor 83 condenses on the CO sensor 85, detection failures occur. Therefore, proposed is to dispose a water discharging portion 84, configured to discharge condensed water, on a flue gas channel in front of the CO sensor 85 (see Patent Document 1 for example).
Meanwhile, to solve the problem of the condensation with respect to the CO sensor, proposed is a combusting device in which an electric heater is disposed in the vicinity of the CO sensor (see Patent Document 2 for example).
Patent Document 1: Japanese Laid-Open Patent Application Publication 2006-213566
Patent Document 2: Japanese Laid-Open Patent Application Publication 8-035655